Remodeling of Failed Pulmonary Valve Autografts After the Ross Procedure

The Ross procedure utilizes a pulmonary autograft for aortic valve replacement, but late autograft failure remains a clinical challenge. In this exploratory study, we characterized structural alterations in failed pulmonary autografts using digital morphometric analysis. Five autografts explanted because of regurgitation were compared with six autopsy control pulmonary valves using special stains and alpha-smooth muscle actin immunohistochemistry. One histologically most affected section per valve was evaluated using QuPath. Failed autografts showed leaflet thickening, elastosis, fibrosis, and myxomatous matrix accumulation. Compared with controls, autografts had greater maximum leaflet thickness (1.540 vs. 0.447 mm; P = 0.004), cross-sectional area (8.730 vs. 3.045 mm²; P = 0.004), α-SMA-positive area (0.707 vs. 0.046 mm²; P = 0.008), and α-SMA-positive area fraction (0.069 vs. 0.016; P = 0.017). The findings demonstrate extracellular matrix alterations and increased α-SMA immunoreactivity in hotspot regions, suggesting a myxomatous-like remodeling pattern.